FR3063401A1 - ROTOR OF ROTATING ELECTRICAL MACHINE WITH IMPROVED CONFIGURATION - Google Patents

Abstract

The invention relates mainly to a rotor (12) of an electric machine characterized in that - each tooth (35) has at least two arms (42) for connection to the hub (32), - each arm (42) comprises a portion of covering with a permanent magnet (39) corresponding to a portion of the arm (42) vis-à-vis the permanent magnet (39) and in that said covering portion comprises a radial length (Hu) and a thickness ( e) orthoradial, and - a ratio between the radial length (Hu) and the thickness (e) orthoradial is between 1.8 divided by a field (B) of the corresponding permanent magnet (39) and 2.16 divided by the field ( B) of the corresponding permanent magnet (39).

Description

Holder (s): VALEO ELECTRIC EQUIPEMENTS MOTOR Simplified joint-stock company.

Extension request (s)

Agent (s): VALEO EQUIPEMENTS ELECTRIQUES MOTOR Simplified joint-stock company.

154 / ROTOR OF ROTATING ELECTRIC MACHINE WITH IMPROVED CONFIGURATION.

FR 3 063 401 - A1 _ The invention relates mainly to a rotor (12) of an electrical machine, characterized in that

each tooth (35) has at least two arms (42) connecting to the hub (32),

- Each arm (42) comprises a covering part with a permanent magnet (39) corresponding to a part of the arm (42) facing the permanent magnet (39) and in that this covering part comprises a radial length (Hu) and an orthoradial thickness (e), and

- a ratio between the radial length (Hu) and the orthoradial thickness (e) is between 1.8 divided by a field (B) of the corresponding permanent magnet (39) and 2.16 divided by the field (B) of the corresponding permanent magnet (39).

ROTATING ROTARY ELECTRIC MACHINE WITH IMPROVED CONFIGURATION

The present invention relates to a rotary electrical machine rotor with improved configuration. The invention finds a particularly advantageous application in the field of rotating electrical machines, such as an alternator or an electric motor. The invention can be advantageously used with an air conditioning refrigerant compressor for a motor vehicle.

Electric machines are known comprising a stator and a rotor secured to a shaft ensuring the setting in motion of a scroll compressor, the latter being designated by the name of scroll in English. Such a system comprises two spirals cooperating with each other to pump and compress the refrigerant. In general, one of the spirals is fixed, while the other moves eccentrically without turning, so as to pump then trap and compress pockets of fluid between the turns. Such a system is for example described in the document EP1865200.

The rotor of the electric machine comprises a body formed by a stack of sheets of metal sheets held in the form of a package by means of a suitable fixing system. The rotor has poles formed for example by permanent magnets located in housings formed in the magnetic mass of the rotor. Alternatively, in a configuration known as salient poles, the poles are formed by coils wound around the rotor arms.

Furthermore, the stator comprises a body made of laminated sheets to reduce the eddy currents. The body has an annular wall, called the cylinder head, and teeth from the inner periphery of the annular wall. The stator teeth distributed on the cylinder head extend towards the inside of the stator in the direction of the rotor. An air gap exists between the free end of the teeth, defining the inner periphery of the stator body, and the outer periphery of the rotor. The teeth define with the cylinder head notches open towards the inside and intended to receive a winding for the formation of a polyphase stator, for example of the three-phase type. This winding could for example consist of a set of coils electrically insulated from the body of the stator each wound around a corresponding tooth. A so-called concentrated type winding is thus obtained.

The invention aims to improve the existing configuration of such an electric machine.

To this end, the invention relates to an electric machine rotor comprising:

- a body comprising teeth and housings between the teeth,

- at least one permanent magnet positioned in each housing, îo - the body further comprising a hub intended to be mounted on a shaft, characterized in that

each tooth has at least two arms connecting to the hub,

each arm forms a portion of an edge of a housing of a corresponding permanent magnet,

each arm comprises a covering part with a permanent magnet corresponding to a part of the arm facing the permanent magnet and in that this covering part comprises a radial length and an orthoradial thickness, and

- a ratio between the radial length and the orthoradial thickness is between 1.8 divided by a field of the corresponding permanent magnet and 2.16 divided by the field of the corresponding permanent magnet.

The invention thus makes it possible to limit the leakage flow passing through the rotor link arms by saturating them magnetically and to avoid any risk of mechanical degradation of the rotor due to the effect of centrifugal force. The invention also makes it possible to reduce the weight of the machine and to minimize the noise level.

By orthoradial thickness is meant the thickness of the arm measured in a direction perpendicular to a radial plane passing through the center of the arm and equidistant from the axis of the rotor and not axially.

According to one embodiment, a recess is formed between the two arms of the same tooth and in that the tooth comprises a flared portion extending in the extension of each arm forming one face of the recess and in that this face forms an angle with a face of the arm forming a face of the corresponding recess of at least 150 degrees.

According to one embodiment, at least one tooth comprises a fixing hole capable of receiving a fixing member and in that a gap between an edge of the fixing hole and an edge of the corresponding recess is constant.

According to one embodiment, an external diameter of the rotor is between 60mm and 70mm.

According to one embodiment, the permanent magnets are made of rare earth.

According to one embodiment, a thickness of each arm is between 0.4 and 0.6mm.

According to one embodiment, the thickness of each arm is of the order of 0.5mm.

According to one embodiment, the useful overlap length is between 0.7mm and 4.2mm.

According to one embodiment, said rotor comprises means for radial retention of the permanent magnets.

According to one embodiment, the radial retaining means consist of lips extending on either side of the teeth of said rotor.

According to one embodiment, said rotor comprises members for plating permanent magnets towards the corresponding lips.

According to one embodiment, each plating member is positioned in a corresponding housing between the hub and the corresponding permanent magnet.

According to one embodiment, the body is formed by a package of laminated sheet.

The invention also relates to a rotary electric machine characterized in that it comprises a rotor as defined above.

According to one embodiment, said rotary electric machine is configured to operate at a voltage of less than 350 volts.

The invention will be better understood on reading the description which follows and on examining the figures which accompany it. These figures are given only by way of illustration but in no way limit the invention.

Figure 1 is a cross-sectional view of a rotary electrical machine according to the present invention;

Figure 2 is a side view of the rotary electrical machine according to the present invention;

Figure 3 is a top view of the stator of the rotary electrical machine according to the present invention;

FIG. 4 is a partial section view of the stator of the rotary electric machine according to the present invention;

Figure 5 is a schematic representation of the triangle coupling of the phases of the rotary electric machine according to the present invention;

FIG. 6 is a graphical representation of the evolution of the efficiency and axial length parameters of the stator body of the electric machine as a function of the number of turns for each coil;

FIG. 7 is a detailed view illustrating the overlap zone between a magnet and the link arms of the rotor of the rotary electric machine according to the present invention;

FIG. 8 is a representation of the evolution of the leakage flux passing through the rotor arm and of the mechanical stresses applied to the package of rotor sheets as a function of the thickness of a rotor connecting arm.

Identical, similar, or analogous elements keep the same reference from one figure to another.

FIG. 1 represents a rotary electrical machine 10 comprising a polyphase stator 11 surrounding a rotor 12 of axis X intended to be mounted on a shaft (not shown). The stator 11 is intended to be carried by a casing (not shown) configured to carry the shaft in rotation via ball and / or needle bearings as visible for example in the document

EP1865200 cited above. This rotary electrical machine 10 may belong to a compressor used for compressing the refrigerant fluid of an air conditioner of a motor vehicle. As a variant, the machine 10 can operate in alternator mode. Preferably, the rotary electrical machine 10 is advantageously configured to operate at a voltage of less than 350 volts.

As can be seen in Figure 3, the stator 11 has an axis Y intended to be coincident with the axis X of the rotor 12 when the machine 10 is in an assembled state. The stator 11 comprises a body 16 in the form of a packet of laminated sheets having at its external periphery an annular wall

17, called the cylinder head, and teeth 18 coming from the internal periphery of the cylinder head 17, as shown in FIG. 4. These teeth 18 are distributed circumferentially in a regular manner and extend inwards towards the rotor 12, such as a permanent magnet rotor described in more detail below.

The teeth 18 delimit two by two of the notches 21, two successive notches 21 thus being separated by a tooth 18. These teeth 18 each have at their free end two flanges 22 extending circumferentially on either side of the tooth 18. The free ends of the teeth 18 delimit, in a known manner, an air gap with the external periphery of the rotor 12 of the rotary electric machine 10.

The stator 11 further comprises a three-phase winding 25 comprising a plurality of coils 26 to form the different poles of the stator 11. Each coil 26 is formed by a plurality of turns surrounding a corresponding tooth 18. The coils 26 are made so that the same notch 21 receives two half-coils. A so-called concentrated type winding 25 is thus obtained.

The wires of the coils 26, such as copper or aluminum wires covered with an electrically insulating layer, such as for example enamel, are each wound around a tooth 18. This winding operation 25 could for example be performed using a centrally hollow needle to allow passage of one or more wires in parallel forming the coil 26. This needle moves circumferentially, axially, and radially with respect to the stator 11. The coil 25 can be produced in situ, that is to say directly around the teeth 18 of the stator 11. Alternatively, the winding 25 can be produced on attached teeth 18 which are then fixed to the cylinder head of the stator 11 via a suitable connection system.

Preferably, the stator 11 is equipped with notch insulators 29 taking, for example, the form of a thin membrane, made of an electrically insulating and heat conductive material. This thin membrane is folded, so that each notch insulator 29 is inserted between a coil 26 and the internal walls of the notches 21 of the stator 11.

As illustrated in FIG. 5, a distinction is made between the coils 26, the coils Ui used to form the phase U of the machine, the coils Vi used to form the phase V of the machine, as well as the coils Wi used to form the phase W of the machine, for i going from 1 to N. N is in this case 5 but could alternatively have a higher or lower value while remaining at least equal to two.

More precisely, Tj corresponds to a tooth 18 of the stator 11 with j going from 1 to 15 for a stator with 15 teeth. The coils are associated alternately with the different phases of the stator 11. Thus, for a three-phase system U,

V, W, the coil of tooth T1 is associated with phase W, the coil of tooth T2 is associated with phase V, the coil of tooth T3 is associated with phase U, and so on. We thus find the coils 26 associated with the same phase every K teeth, K being the number of phases here equal to three.

In addition, the coils 26 of each phase U, V, W are electrically connected in series. Thus, the coils U1, U2, U3, U4, U5 of phase U are electrically connected in series. The coils V1, V2, V3, V4, V5 of phase V are electrically connected in series. And the coils W1, W2, W3, W4, W5 of phase W are electrically connected in series.

The phases U, V, W of the machine 10 are advantageously coupled in a triangle. Thus, the EU input of phase U is connected with the SW output of phase W. The EW input of phase W is connected with the output SV of phase V. The EV input of phase V is connected with the SU output of phase U.

In order to increase the efficiency of the machine 10, it is necessary to reduce its resistance by increasing the windable section, as well as the number of turns Ns of each coil 26 and the axial length L1 of the stator body 16 (cf. FIG. 2 ). At an iso-filling rate, the reduction in the number of turns Ns corresponds to an increase in the diameter of the wire. Furthermore, to improve the compactness of the machine 10, it is necessary to reduce the length L1 of the stator body 16 while retaining the same torque. For this purpose, it is necessary to increase the number of turns Ns.

In order to optimize the compromise between efficiency and compactness by having an efficiency greater than or equal to 89% and an axial length L1 of the stator body 16 less than or equal to 27mm, the product of the number of turns Ns of each coil 26, the axial length L1 of the stator body 16 expressed in millimeters, and the internal diameter L2 of the stator body 16 expressed in millimeters, that is to say the product NsxL1XL2, is between 38998 and 39142.

Preferably, the number of turns Ns is between 23 and 37, the axial length L1 of the stator body 16 is between 17mm and 27mm, and the internal diameter L2 of the stator body 16 is between 62mm and

67mm.

The table below presents examples of values for an internal diameter L2 of the stator body 16 being 62mm:

| Line number Number of turns Ns Length 11 Yield R | I ¹ 22 28.7 92.9% 2 25 25.2 92.2% 1 ³ 28 22.5 91.5% 1 ⁴ 31 20.3 90.7% 1 5 34 18.5 89.9% 1 6 37 17.0 89.1% I 7 40 15.8 88.2% D 8 43 14.7 87.3% J

The curves C1 and C2 corresponding respectively to the length L1 and to the efficiency R are represented in FIG. 6. It is observed that the values of the first line do not correspond to an acceptable configuration because they do not make it possible to respect the compactness criterion (L1 better than

27mm). In addition, the values of lines 7 and 8 do not allow compliance with the performance criterion imposed (R less than 89%).

The table below presents examples of values for an internal diameter L2 of the stator body 16 equal to 67mm:

Line number Number of turns Ns Length 11 Yield R î 17 34.3 93.4? " 2 20 29.2 92.6% 3 23 25.4 91.7% 4 26 22.4 90.8% 5 29 20.1 89.8% 6 32 18.2 88.8% 7 35 16.7 87.7% 8 38 15.4 86.6%

It is observed that the values of lines 1 and 2 do not correspond to acceptable configurations, because they do not make it possible to comply with the compactness criterion (L1 greater than 27mm). Furthermore, the values of lines 6, 7, and 8 do not allow the performance criterion to be met (R less than 89%).

In a particular embodiment, the stator body 16 has an external diameter L3 of 94mm plus or minus 20%. The axial length L1 of the stator body 16 is of the order of 20mm plus or minus 20%. The number of turns Ns of each coil 26 is of the order of 32 plus or minus 20%. A thickness of the cylinder head 17 of the stator 11 is of the order of 4.5 mm plus or minus 20%. The wire diameter of each coil 26 is around 0.8mm plus or minus 20%.

Furthermore, as can be seen in FIGS. 1 and 7, the rotor 12 of axis X comprises a body 31 formed by a packet of laminated sheet formed by an axial stack of ferromagnetic sheets. The rotor body 31 comprises a hub 32 mounted on the machine shaft and teeth 35 extending radially with respect to the hub 32. Housing 36 is located between the teeth 35. Each housing 36 is delimited by two teeth 35 consecutive, so that there is a circumferential alternation between the teeth 35 and the housings 36.

At least one permanent magnet 39 is positioned in each housing 36. Thus, it will be possible to use a single magnet 39 positioned inside a corresponding housing 36, or two magnets 39 or even more than two magnets per housing 36 stacked axially on top of each other.

The magnets 39 extend radially with respect to the axis X of the rotor 12. A rotor configuration 12 with flux concentration is thus obtained, the lateral faces facing two consecutive magnets 39 being of the same polarity. The magnets 39 are preferably made of rare earth. As a variant, the magnets 39 are made of ferrite depending on the applications and the desired power of the rotary electric machine 10. In this case, the rotor 12 has ten housings 36 and therefore ten poles.

Furthermore, each tooth 35 has two arms 42 for connection to the hub 32, as is clearly visible in FIG. 7. Each arm 42 forms a portion of a housing edge 36 of a corresponding magnet 39. Each arm 42 comprises a covering part with a magnet 39 corresponding to the part of the arm 42 facing the magnet 39 having a radial length Hu and a thickness e measured in an orthoradial direction relative to the axis X.

Preferably, in order to obtain an optimum compromise between the magnetic performance and the mechanical rigidity of the rotor 12, the ratio between the radial length Hu and the thickness e of an arm 42 is between 1.8 divided by the field B of the corresponding magnet 39 and 2.16 divided by the field B of the corresponding magnet 39.

In FIG. 8 where the curves C3 and C4 respectively represent the evolution of the mechanical stresses applied to the package of sheets of the rotor and the evolution of the leakage flux, the thickness e of an arm 42 is between 0.3mm and 0.8mm in order to comply with the limit at rupture of the sheet metal package Lim_r and the maximum admissible leakage flow Lim_f.

In addition, a recess 45 is formed between the two arms 42 of the same corresponding tooth 35. The tooth 35 comprises a flared portion 46 extending in the extension of each arm 42 forming one face of the recess 45. This face forms an angle A with one face of the arm 42 forming another face of the recess 45 corresponding to '' at least 150 °.

In an exemplary embodiment, the rotor 12 has an external diameter L4 of between 60mm and 70mm and an internal diameter L5 of between 15 and 20 mm (cf. FIG. 1). The thickness of each arm 42 is between 0.4 and

0.6mm, and is preferably around 0.5mm. The length of the useful overlap Hu is between 0.7mm and 4.2mm.

In the example shown in Figures 1 and 7, each tooth 35 further comprises a fixing hole 47 adapted to receive a fixing member, such as a rivet, to hold together the sheets of the rotor 12. In order to optimize the passage of the flux in the tooth 35, a difference L6 measured in a plane perpendicular to the axis X between an edge of the fixing hole 47 and an edge of the corresponding recess 45 is constant. Alternatively, some teeth 35 of the rotor 12 have a fixing hole 47 but not all.

In addition, lips 50 are located on the side of the free end of each tooth 35. These lips 50 extend on either side of each tooth 35. These lips 50 thus constitute means for radially retaining the magnets 39 Alternatively, the housings 36 for the magnets 39 can be closed at their outer periphery.

Plating members 53, such as flat springs, ensure the plating of the magnets 39 towards the corresponding lips 50, as illustrated in FIG. 7. Each plating member 53 is positioned in a corresponding housing 36 between the hub 32 and the corresponding magnet 39.

Of course, the foregoing description has been given by way of example only and does not limit the scope of the invention from which one would not depart by replacing the various elements with any other equivalent.

Furthermore, the various features, variants, and / or embodiments of the present invention can be combined with one another in various combinations, insofar as they are not incompatible or mutually exclusive of one another.

Claims (14)

1. Rotor (12) of an electrical machine comprising: a body (31) comprising teeth (35) and housings (36) between the teeth (35), 5 - at least one permanent magnet (39) positioned in each housing (36), - the body (31) further comprising a hub (32) intended to be mounted on a shaft, characterized in that îo - each tooth (35) comprises at least two arms (42) connecting to the hub (32), each arm (42) forms a portion of an edge of a housing (36) of a corresponding permanent magnet (39), each arm (42) comprises a covering part with a 15 permanent magnet (39) corresponding to a part of the arm (42) facing the permanent magnet (39) and in that this covering part comprises a radial length (Hu) and a thickness (e) orthoradiale, and - a ratio between the radial length (Hu) and the orthoradial thickness (e) is between 1.8 divided by a field (B) of the magnet 20 corresponding permanent (39) and 2.16 divided by the field (B) of the corresponding permanent magnet (39). 2. Rotor according to claim 1, characterized in that a recess (45) is formed between the two arms (42) of the same tooth (35) and in that the tooth (35) comprises a flared portion (46 ) extending into the 25 extension of each arm (42) forming a face of the recess (45) and in that this face forms an angle (A) with a face of the arm (42) forming a face of the recess (45) corresponding to '' at least 150 degrees. 3. Rotor according to claim 2, characterized in that at least one tooth (35) comprises a fixing hole (47) capable of receiving a member for 30 fixing and in that a gap (L6) between an edge of the fixing hole (47) and an edge of the corresponding recess (45) is constant. 4. Rotor according to any one of claims 1 to 3, characterized in that an external diameter (L4) of the rotor (12) is between 60mm and 70mm. 5. Rotor according to any one of claims 1 to 4, characterized in that the permanent magnets (39) are made of rare earth. 5 6. Rotor according to any one of claims 1 to 5, characterized in that a thickness of each arm (45) is between 0.4 and 0.6mm. 7. Rotor according to claim 6, characterized in that the thickness of each arm (45) is of the order of 0.5mm. îo 8. Rotor according to any one of claims 1 to 7, characterized in that the radial length (Hu) is between 0.7mm and 4.2 mm. 9. Rotor according to any one of claims 1 to 8, characterized in that it comprises radial retaining means (50) of the permanent magnets (39). 15 10. Rotor according to claim 9, characterized in that the radial retaining means consist of lips (50) extending on either side of the teeth (35) of said rotor (12). 11. Rotor according to any one of claims 1 to 10, characterized in that it comprises plating members (53) of the magnets 20 perms (39) to the corresponding lips (50). 12. Rotor according to claim 11, characterized in that each plating member (53) is positioned in a housing (36) corresponding between the hub (32) and the permanent magnet (39) corresponding. 13. Rotor according to any one of claims 1 to 12, characterized in that the body (31) is formed by a package of laminated sheet. 14. Rotating electric machine (10) characterized in that it comprises a rotor (12) as defined according to any one of the preceding claims. 1/4